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/*

FUNCTION

<<mbtowc>>---minimal multibyte to wide char converter

INDEX

        mbtowc

ANSI_SYNOPSIS

        #include <stdlib.h>

        int mbtowc(wchar_t *<[pwc]>, const char *<[s]>, size_t <[n]>);

TRAD_SYNOPSIS

        #include <stdlib.h>

        int mbtowc(<[pwc]>, <[s]>, <[n]>)

        wchar_t *<[pwc]>;

        const char *<[s]>;

        size_t <[n]>;

DESCRIPTION

When MB_CAPABLE is not defined, this is a minimal ANSI-conforming

implementation of <<mbtowc>>.  In this case,

only ``multi-byte character sequences'' recognized are single bytes,

and they are ``converted'' to themselves.

Each call to <<mbtowc>> copies one character from <<*<[s]>>> to

<<*<[pwc]>>>, unless <[s]> is a null pointer.  The argument n

is ignored.

When MB_CAPABLE is defined, this routine calls <<_mbtowc_r>> to perform

the conversion, passing a state variable to allow state dependent

decoding.  The result is based on the locale setting which may

be restricted to a defined set of locales.

RETURNS

This implementation of <<mbtowc>> returns <<0>> if

<[s]> is <<NULL>> or is the empty string;

it returns <<1>> if not MB_CAPABLE or

the character is a single-byte character; it returns <<-1>>

if n is <<0>> or the multi-byte character is invalid;

otherwise it returns the number of bytes in the multibyte character.

If the return value is -1, no changes are made to the <<pwc>>

output string.  If the input is the empty string, a wchar_t nul

is placed in the output string and 0 is returned.  If the input

has a length of 0, no changes are made to the <<pwc>> output string.

PORTABILITY

<<mbtowc>> is required in the ANSI C standard.  However, the precise

effects vary with the locale.

<<mbtowc>> requires no supporting OS subroutines.

*/

#include <stdlib.h>

int

_DEFUN (mbtowc, (pwc, s, n),

        wchar_t *pwc _AND

        const char *s _AND

        size_t n)

{

#ifdef MB_CAPABLE

        static int state;

        return _mbtowc_r (_REENT, pwc, s, n, &state);

#else /* not MB_CAPABLE */

        if (s == NULL)

                return 0;

        if (n == 0)

                return -1;

        if (pwc)

                *pwc = (wchar_t) *s;

        return (*s != '\0');

#endif /* not MB_CAPABLE */

}